Impact socket wrench tool

ABSTRACT

A socket wrench capable of reciprocatory sliding motion in the direction of its axis is rotatable thereabout by a preferably hydraulic driving motor. A vibratory impact device is mounted between the motor and the wrench to impart reciprocatory impacts to the rotating wrench, and a slip clutch between the motor and the impact device prevents vibrations from reaching the motor.

United States Patent [1 1 Theurer Sept. 18, 1973 IMPACT SOCKET WRENCH TOOL [75} Inventor:

[73] Assignee: Franz Plasser Bahnbaumaschinen Industriegesellschaft m.h.H., Vienna, Austria [22] Filed: Nov. 3, 1971 [21] Appl. No.: 195,278

Josef Theurer, Vienna, Austria [30] Foreign Application Priority Data 3,585,817 6/1971 McCafierty et a1 173/12 2,707,892 5/1955 Holmes 173/93 3,628,461 12/1971 Plasser et al. 104/17 R Primary ExaminerErnest R. Purser Att0rneyl(urt Kelman [57] ABSTRACT A socket wrench capable of reciprocatory sliding motion in the direction of its axis is rotatable thereabout by a preferably hydraulic driving motor. A vibratory impact device is mounted between the motor and the wrench to impart reciprocatory impacts to the rotating wrench, and a slip clutch between the motor and the impact device prevents vibrations from reaching the motor.

12 Claims, 3 Drawing Figures IMPACT SOCKET WRENCH TOOL The present invention relates to improvements in an impact socket wrench tool wherein the wrench is rotatable by a driving motor and a vibratory impact device is mounted between the driving motor and the wrench. In one particular and preferred aspect, this invention is directed to a mobile machine for simultaneously fastening a pair of rail fastening bolts arranged on respective sides of a track rail, wherein a pair of such tools are mounted on a mobile frame.

In known tools of this type, the socket wrench is capable of rotary motion about the axis thereof and of reciprocatory sliding motion in the direction of the axis. The vibratory impact device, various designs of which are also well known, effectuates the reciprocatory sliding motion during rotation of the wrench.

It will be obvious to those skilled in the art that the socket wrench may be replaced by a screwdriver bit to provide a power-driven impact screwdriver, or by a drilling bit to provide a power-driven impact drill so that the tool of the invention may be used either as a screwdriver for fastening screws or as a drill for tapping holes in railroad ties, for instance. It is, therefore, to be understood that the term socket wrench includes screwdriver or drilling bits used in equivalent rotary impact tools well known in this art.

In track construction and renewal, many problems arise in connection with the fastening and loosening or removal of the rail fastening bolts or the nuts holding them in position. Being constantly exposed to the weather, the threaded connections of the fastening means tend to rust so that considerably more torque is required for loosening the old connections than for driving a new bolt home. Furthermore, standards set by the railroads require a rather narrow range of tolerances in the torque of the wrench for driving the bolt or nut home to prevent damage to the threads or breakage of the fastening elements, the torque being often limited to about 18 to 22 kpm.

These requirements were difficult to fulfill with known power-driven wrenches because the torque required for loosening weather-beaten rail fastening ele ments involved the use of extra-powerful drives while, on the other hand, such drives are not readily adapted to the narrow range of low torque requirements for driving the bolts or nuts home. In an effort to overcome these difficulties, it has been proposed to use impact devices mounted between the driving motor and thewrench to reduce the driving force, pneumatic and electric motors having been used for this purpose.

In pneumatic drives, large air compressors are needed for relatively small wrenches, which makes the use of such tools impractical in mobile track maintenance and renewal apparatus since there is only little space available for the wrenches in this type of apparatus. In electric drives, it is also necessary to provide a relatively large electric power source, with the necessary auxiliary equipment, since no connection with existing electric power lines is possible in mobile apparatus. Furthermore, it is necessary to provide reduction gears in such power-driven wrenches to obtain the required torque. This makes the tools not only more expensive but increases their size and, thus, the space requirements.

In addition, problems arise in pneumatic and electro motors in connection with meeting the exacting requirements of the railroads in respect to the torque of the wrench. Slip clutches used in conventional tools of this type to limit the torque of the wrench are subjected to many exterior influences whose effects cannot be calculated inadvance. Since such impact wrenches are used almost exclusively outdoors, the friction coefficient of the disk clutch linings changes constantly in response to the prevailing weather and humidity. Thus, the torque must constantly be readjusted experimentally. Oil leaks to the clutch linings also tend to change the friction coeflicient so that, in effect, an exact and constant limitation of the torque is not attainable with the known power impact wrenches. This disadvantage in the use of such wrenches in track maintenance and renewal work is further compounded by the fact that such slip clutches wear exceedingly fast.

In view of the above disadvantages of pneumatic and electro drives for impact wrenches, it has been proposed to use socket wrenches in track work which are driven directly by hydraulic motors. Since most mobile track maintenance machines have hydraulic drive systems for various tools, use may be made of these systems for driving the wrenches without requiring an additional power plant while, at the same time, enabling the torque to be accurately controlled by pressure relief valves arranged in the hydraulic fluid delivery lines. However, the efficiency of such power-driven wrenches has also proven to be limited, particularly in respect of loosening weather-beaten bolts or nuts. To overcome this, it was necessary to provide a relatively powerful hydraulic motor, requiring a considerable increase in the capacity of the hydraulic system particularly in such machines which use a plurality of power.- driven wrenches.

Overcoming this disadvantage by incorporating an impact device in such hydraulically-driven power wrenches involved the difficulty that hydraulic fluid is incompressible, i.e., it is a rigid and inelastic driving medium in contrast to a compressed air or electric driving medium. Thus, the vibrations emanating from the impact device cannot be absorbed by the hydraulic drive.

It is the primary object of the present invention to provide an impact socket wrench, screwdriver or drill,

wherein the driving motor for rotating the socket wrench, screwdriver or drilling bit may be not only pneumatically or electrically but also hydraulically operated so that the advantages of hydraulic drives may be used for the first time in such impact tools while holding the dimensions of the driving motor to a minimum.

The above and other objects of this invention are accomplished by arranging between the driving motor, which is preferably hydraulically driven, and the impact device a means for absorbing vibrations of the vibratory impact device, this means preventing the vibrations from reaching the driving motor. This means may be a slip or disk clutch of a known type.

In the impact socket wrench tool of the invention, the means for absorbing vibrations or preventing them from reaching the driving motor does not serve to limit the torque of the socket wrench but is used solely to prevent the transmission of the reciprocatory impacts or vibrations from the impact device to the motor. Of course, this vibration blocking means may be used in power-driven impact wrenches of all types, in addition to the slip clutch designed to limit the torque of the wrench but it is of primary advantage with hydraulic driving motors, in which combination it makes it possible for the first time to use a hydraulic driving motor with an impact device, as explained hereinabove.

In the hydraulic tool of the invention, the exact ad justment of the torque of the wrench may be effected in a known manner by mounting pressure relief valves in the hydraulic fluid delivery line to the driving motor, such adjustment being calculated accurately as a function of the hydraulic fluid pressure which determines the rotational speed of the driving motor as well as the vibratory motion of the impact device. A hydraulic drive, furthermore, requires only a fraction of the driving power required, for instance, for the compressor of a compressed air drive, thus making the use of such tools-even more advantageous in mobile track working apparatus.

While slip clutches are preferred, other means for absorbing or blocking vibrations of the vibratory impact device, including hydraulically operated means, may be used in the tool of the present invention. The relative rotational movement between the coupling parts of the tool involves only a few millimeters per impact or axial movement and the coupling parts are at rest in relation to each other between impacts. In other words, there is no continuous slippage so that the clutch disk linings are not overheated as is the case with the use of such clutches for limiting the torque. In actual use, it has been shown that the slip clutches are subject to very little wear in the tools of this invention so that the tools have a long life.

While, as indicated hereinabove, the torque for fastening bolts or nuts is limited to about 20 kpm and loosening of rusted connections may require a torque of 200 kpm or more, it is generally sufficient to arrange the slip clutch fora torque of about 4 kpm. Such a coupling requires very little space and thus makes it possible to provide a very compact power-driven wrench with all the indicated advantages. Since the slip clutch is not used to determine an exact torque but merely serves to absorb or block vibrations, changes in the friction coefficient of the clutch disk linings make no substantial difference in the operation of the tool.

According to a preferred feature, the socket wrench is slidingly movable in the direction of its axis into driving engagement with the impact device and driving motor against the bias of a spring so that it will not be rotated when the socket first engages the bolt head or nut and thus avoids damaging the same. The sliding stroke may be adjustable. This arrangement also makes it possible to increase the rotary speed of the wrench and thus its efficiency. In known hydraulically-driven power wrenches, the rotational speed of the wrench is about 90 rpm while the initial speed of the wrenches of this invention may be about 2,000 to 3,000 rpm, which speed is reduced by the impact device to about 600 to 1,000 rpm.

The axially slidable socket wrench may be coupled to the driving motor directly by the parts of the impact device, in which case the housing of the impact device is continuously rotated by the driving motor and is coupled with the wrench only after the wrench has engaged the bolt head or nut and has been axially moved inwardly. However, the life of the impact device will be increased if a jaw clutch is mounted between the impact device and the vibration absorbing or blocking means so that the impact device is at rest until the wrench has been coupled to the driving motor by the axial sliding motion thereof.

While the impact socket wrench tool of the present invention may be used with advantage as an individual tool, it will be particularly useful in conjunction with a mobile machine for renewing track, where space considerations are of the utmost importance. In such use, it will be preferred to mount a pair of such tools on a mobile frame for simultaneous engagement with a respective pair of rail fastening bolts arranged on respective sides of a track rail. A plurality of such pairs of socket wrench tools may be mounted on a common frame spaced from each other in the direction of the track and for relative movement in respect of each other and the frame. A single relatively small hydraullic supply system, including a motor-driven hydraulic pump, may then be used for all the driving motors of the tools since hydraulic motors for such tools require relatively little hydraulic fluid for effective operation.

Since automatically working rail and/or tie laying devices require automatic accurate centering of the wrenches over the rail fastening elements, a registering boss may be associated with each pair of tools to cooperate with a part of the rail fastening means.

In one embodiment of this invention, a pair of hydraulically-driven wrench tools are mounted on a wheelbarrow-type carriage. The carriage comprises a running gear and a carrier beam having two ends mounted on the running gear for vertical and horizontal pivoting movement, the running gear being positioned intermediate the carrier ends. Handle means is provided at one of the carrier ends while a hydraulic pump and motor means for driving the pump are mounted on the other carrier end. The pump delivers hydraulic fluid to the driving motors of each tool mounted on the carriage. Such a mobile machine is very light since the power requirements are minimal and may, therefore, be handled by a single operator while having a double capacity.

The above and other objects, advantages and features of the present invention will become better understood by reference to the following detailed description of now preferred embodiments thereof, taken in conjunction with the accompanying drawing wherein FIG. 1 is a longitudinal section of an impact socket wrench tool according to this invention;

FIG. 2 is a side view of a mobile machine for fasten ing rail fastening bolts by means of such impact socket wrench tools; and

FIG. 3 is a side view of a manually movable machine of this type.

Referring now to the drawing and first to FIG. 1, there is shown an impact socket wrench tool comprising essentially three coaxially arranged and associated parts, i.e., a replaceably mounted socket wrench 3, a hydraulically driven driving motor 1 for rotating the socket wrench, and a vibratory impact device 2 mounted between the driving motor and the socket wrench for effectuating reciprocatory sliding motion during rotation of the wrench, the wrench being capable of rotary motion about the axis thereof and of the reciprocatory sliding motion in the direction of the axis.

A slip clutch in the form of a disk clutch 4 is arranged between the driving motor 1 and the impact device 2 for absorbing vibrations of the vibratory impact device, one part 4a of the clutch being keyed to the shaft of motor 1 for rotation therewith and the other clutch part 4b being keyed to a stub shaft 22 coupled to the impact device for rotation with the stub shaft.

A protective casing 5 surrounds the clutch 4, one end of the casing being bolted to the hydraulic motor 1 while the other casing end is bolted to housing 7 which surrounds the impact device 2. A closure disk 6 is interposed between the casing 5 and housing 7, the closure disk having a central bore receiving the clutch part 4b and stub shaft 22 which is rotatably journaled in the central bore of the closure disk.

The slip clutch 4 is capable of transmitting a torque of about 4 kpm although the socket wrench 3 may be subjected to a torque as high as 200 kpm, or more, which may be required to remove heavily rusted bolts. Such high torques are achieved with a hydraulic motor of 2,000 to 3,000 rpm and the impact obtained by the impact device 2. Each of the series of repeated impacts imparted to the wrench by the impact device 2 causes the disks of the clutch to slip a little, i.e., a few millimeters, whereby the vibrations of the impact tool are so absorbed as not to be transmitted to the hydraulic motor, thus protecting the operation of the motor from the vibrations. However, the disk clutch does not continuously slip during normal operation of the tool so that the wear of the clutch disks is very low.

A wrench holder 8 is rotatably joumaled in the lower end of housing 7 by means of roller bearings 9. 9a, 9b. A socket wrench rod 10 is mounted in the holder end adjacent the impact device 2 for reciprocatory sliding motion in the direction of the tool axis, the rod 10 having a hexagonal portion 10a engaging the holder so as to be non-rotatory in relation thereto and thus rotating therewith. The hexagonal end of the socket wrench rod 10 carries one coupling part 2a of the impact device 2 while the other impact device part 2b, which carries the impact claws, is coupled to the disk clutch 4, a jaw clutch 11 being provided in the illustrated embodiment between the disk clutch 4 and the other impact device part 2b.

If no jaw clutch is provided, the impact claw carrying impact device part 2b is rotated continuously by the hy-- draulic motor 1 and the impact device parts 2a, 2b serve simultaneously as coupling between the motor and the socket wrench, i.e., when the socket wrench 3 is engaged with a bolt head to cause axial inward movement of the wrench, the coupling part 2 is moved into engagement with impact device part 2b'so as to rotate therewith. 7

In the illustrated embodiment, the impact device parts 20, 2b are in constant engagement and the impact device is engaged with the hydraulic motor and rotated thereby upon the axial inward movement of the socket wrench and the corresponding engagement of jaw clutch 11. The axial sliding movement of the socket wrench 3 may be preferably adjustably limited by a suitable stop (not shown).

A helical compression spring 12 is mounted on rod 10 to bias the socket wrench 3 outwardly, one end of the spring resting against annular spring seat 13 supported by holder 8 and the other spring end pressing against annular spring seat 14. The spring seat 14 is slidably mounted on rod 10 and engages a slide ring 15 engaged with the socket wrench 3 which is slidably journaled in wrench holder 8 but is non-rotatary in relation thereto so as to rotate with the holder. Thus, unless and until the socket wrench is depressed upon engagement with a bolt head, it is out of engagement with the hydraulic motor 1, only the inward axial movement of the wrench against the bias of compression spring 12 coupling the wrench to the motor.

In the illustrated embodiment, the socket wrench is replaceably mounted in the tool, the mounting including telescoping sleeves 17, 18 which surround the wrench holder 8, sleeve 18 being attached to impact device housing 7 while sleeve 17 is attached to the holder by screws 16, a helical spring 19 being mounted between the telescoping sleeves and locking balls 20 being arranged in an annular space 21 between the socket wrench 3 and the sleeve 17 to exert a radial pressure on the wrench and maintain it in the holder. When the screws 16 are removed, the sleeve 17 may be moved axially into sleeve 18 to release the radial pressure on balls 20 so as to enable the wrench 3 to be removed from the holder.

In operation, the outwardly biased socket wrench 3 is at rest when it is engaged with a bolt head until the tool is moved down to depress the wrench and move it axially inwardly in respect of wrench holder 8 against the bias of compression spring 12. This causes a corresponding axial movement of the rod 10 and the impact device 2, which is coupled therewith, to engage clutch 11 and thus to couple the wrench to driving motor 1. Thus, the bolts will not be damaged by rotating tool parts when they are first engaged. Also, after the bolt has been fastened or unfastened, depending on the direction of rotation of the wrench, and the tool is lifted again to permit the wrench to be outwardly biased under the pressure of spring 12, the wrench will be at rest again so taht no jamming will occur due to torque forces applied to the bolt.

FIG. 2 shows a mobile machine for simultaneously fastening a pair of rail fastening bolts 28 arranged on respective sides of a track rail 26, as is common to fasten the rails of a railroad track to the ties 27. The machine comprises a partially illustrated frame 24 mounted for mobility on the track by means of running gears 25. If desired, such a'mobile machine may be used in conjunction with suitable machinery for renewing the track, wherein it is necessary first to remove rail fastening bolts 28 from the old rails and then to fasten the bolts on the new rails.

The machine frame 24 has guide rails 29 extending in the direction of the track and cross rails extending transversely thereof to enable a plurality of tool carriers 30 to be moved relatively to each other and to the frame, the tool carriers being spaced from each other and each vertically adjustably supporting a pair of impact socket wrench tools 23 arranged for simultaneous engagement with a respective pair of rail fastening bolts 28. The tools are of the type described hereinabove and illustrated in FIG. 1.

In the illustrated mobile machine, two tool carriers 30 are associated with each rail 26 and are movably mounted on the frame spaced from each other in the direction of the track so that work may be done simul taneously on two successive rail fastening means, each carrier running on rollers 31 on the track rails so that the tools may be centered above the respective rail fastening bolts 28, working being done simultaneously on eight bolts by this arrangement.

A registering boss or dog 32 is associated with each pair of socket wrench tools 23 to cooperate with a part of the rail fastening means. A hydraulic motor 33 is operatively connected with each registering boss so as to lift the same when the machine is moved along the track and lower it into engagement with a cooperating rail fastening means part when the machine is at rest. Each carrier is individually positionable so as to take into account differing crib widths, the spacing between two carriers associated with the same rail 26 being automatically adjustable by an interconnecting hydraulic motor 34 or any other suitable adjustable spacing device, such as a threaded spindle drive.

It will be noted that the machine frame 24 may continue to move along the track while the tool carriers remain at rest, i.e., while the tools are operated, since the carriers 30 may be continuously moved along guide rails 29. After each operation, the coupled tool carriers 30 may be rapidly moved to the next pair of ties by means of a drive 35 operatively connected to one of the carriers.

FIG. 3 shows a manually movable machine of this general type, wherein wheelbarrow-like carriage 39 supports a pair of hydraulically driven socket wrench tools 36 of the same type as shown in FIG. 1 for simultaneously working on a pair of rail fastening bolts 28 arranged on respective sides of track rail 26. The carriage 39 comprises a running gear 39b and a carrier beam 39a is mounted on the running gear for vertical and horizontal pivoting movement about a universal pivot 39c. The running gear is positioned intermediate the ends of the carrier, and handle 40 is mounted on one end of the carrier beam while the pump 37 for delivering hydraulic fluid to the driving motors of the tools 36 and a motor 38 for driving the pump 37 are mounted on the other carrier end. This arrangement provides an almost perfect balance between the weight of the socket wrench tools 36 and their drive so that a light machine is provided which can be handled with ease. A means 41 for adjusting the driving motor torque is provided, the illustrated means comprising a control in the hydraulic fluid delivery line to adjust the fluid pressure delivered to the driving motors and thus the rotational speed of the motors. A control line operated by lever 42 mounted on handle 40 enables an operator to adjust the control 41.

I claim:

1. An impact socket wrench tool comprising 1. a socket wrench capable of rotary motion about the axis thereof and of reciprocatory sliding motion in the direction of the axis,

2. a hydraulically driven driving motor for rotating the socket wrench,

3. a vibratory impact device mounted between the driving motor and the socket wrench for effectuating the reciprocatory sliding motion during rotation of the wrench, and

4. means for absorbing vibrations of the vibratory impact device arranged between the driving motor and the impact device.

2. The impact socket wrench tool of claim 1, wherein the vibration absorbing means is a slip clutch.

3. The impact socket wrench tool of claim 2, wherein the slip clutch is a disk clutch.

4. The impact socket wrench tool of claim 1, further comprising a compression spring means mounted between the wrench and the impact device to couple the wrench resiliently to the impact device and driving motor.

5. The impact socket wrench tool of claim 4, wherein the impact device comprises two cooperating parts, one of the impact device parts being coupled to the wrench and the other impact device part being coupled to the driving motor.

6. The impact socket wrench tool of claim 4, further comprising a jaw clutch between the impact device and the vibration absorbing means.

7. A mobile machine for simultaneously fastening a pair of rail fastening bolts arranged on respective sides of a track rail, comprising 1. a frame mounted for mobility on the track, and

2. a pair of impact socket wrench tools mounted on the frame for simultaneous engagement with a respective pair of the bolts, each tool comprising a. a socket wrench capable of rotary motion about the axis thereof and of reciprocatory sliding motion in the direction of the axis,

b. a hydraulically driven driving motor for rotating the socket wrench,

c. a vibratory impact device mounted between the driving motor and the socket wrench for effectuating the reciprocatory sliding motion during r0- tation of the wrench, and

(1. means for absorbing vibrations of the vibratory impact device arranged between the driving motor and the impact means.

8. The mobile machine of claim 7, comprising a plurality of said pairs of socket wrench tools mounted on the frame spaced from each other in the direction of the track and for relative movement in respect of each other and the frame.

9. The mobile machine of claim 7, further comprising a registering boss associated with said pair of socket wrench tools and cooperating with a part of the rail fastening means.

10. The mobile machine of claim 7 further comprising means for adjusting the driving motor torque.

11. The mobile machine of claim 7, wherein the frame is a wheelbarrow-like carriage, and further comprising a pump for delivering hydraulic fluid to the driving motors and motor means driving the pump.

12. The mobile machine of claim 11, wherein the wheelbarrow-like carriage comprises a running gear, a carrier having two ends mounted on the running gear for vertical and horizontal pivoting movement, the running gear being positioned intermediate the ends of the carrier, handle means at one of the carrier ends, and the pump and motor means being mounted on the other carrier end. 

1. An impact socket wrench tool comprising
 1. a socket wrench capable of rotary motion about the axis thereof and of reciprocatory sliding motion in the direction of the axis,
 2. a hydraulically driven driving motor for rotating the socket wrench,
 3. a vibratory impact device mounted between the driving motor and the socket wrench for effectuating the reciprocatory sliding motion during rotation of the wrench, and
 4. means for absorbing vibrations of the vibratory impact device arranged between the driving motor and the impact device.
 2. a hydraulically driven driving motor for rotating the socket wrench,
 2. The impact socket wrench tool of claim 1, wherein the vibration absorbing means is a slip clutch.
 2. a pair of impact socket wrench tools mounted on the frame for simultaneous engagement with a respective pair of the bolts, each tool comprising a. a socket wrench capable of rotary motion about the axis thereof and of reciprocatory sliding motion in the direction of the axis, b. a hydraulically driven driving motor for rotating the socket wrench, c. a vibratory impact device mounted between the driving motor and the socket wrench for effectuating the reciprocatory sliding motion during rotation of the wrench, and d. means for absorbing vibrations of the vibratory impact device arranged between the driving motor and the impact means.
 3. The impact socket wrench tool of claim 2, wherein the slip clutch is a disk clutch.
 3. a vibratory impact device mounted between the driving motor and the socket wrench for effectuating the reciprocatory sliding motion during rotation of the wrench, and
 4. means for absorbing vibrations of the vibratory impact device arranged between the driving motor and the impact device.
 4. The impact socket wrench tool of claim 1, further comprising a compression spring means mounted between the wrench and the impact device to couple the wrench resiliently to the impact device and driving motor.
 5. The impact socket wrench tool of claim 4, wherein the impact device comprises two cooperating parts, one of the impact device parts being coupled to the wrench and the other impact device part being coupled to the driving motor.
 6. The impact socket wrench tool of claim 4, further comprising a jaw clutch between the impact device and the vibration absorbing means.
 7. A mobile machine for simultaneously fastening a pair of rail fastening bolts arranged on respective sides of a track rail, comprising
 8. The mobile machine of claim 7, comprising a plurality of said pairs of socket wrench tools mounted on the frame spaced from each other in the direction of the track and for relative movement in respect of each other and the frame.
 9. The mobile machine of claim 7, further comprising a registering boss associated with said pair of socket wrench tools and cooperating with a part of the rail fastening means.
 10. The mobile machine of claim 7 further comprising means for adjusting the driving motor torque.
 11. The mobile machine of claim 7, wherein the frame is a wheelbarrow-like carriage, and further comprising a pump for delivering hydraulic fluid to the driving motors and motor means driving the pump.
 12. The mobile machine of claim 11, wherein the wheelbarrow-like carriage comprises a running gear, a carrier having two ends mounted on the running gear for vertical and horizontal pivoting movement, the running gear being positioned intermediate the ends of the carrier, handle means at one of the carrier ends, and the pump and motor means being mounted on the other carrier end. 